Approximately 400 billion dollars is spent each year in treatment of back pain and sleep disorders. Of the top 100 physician prescribed and over the counter medications 75 are for spine and muscle pain or inflammation and for muscle tension or sleep disorders. According to the Centers for Disease Control, anti-inflammatories, anti-spasmodic muscle relaxants and sleep inducing sedatives are responsible for over 100,000 deaths from overdose each year. It is widely believed that these medicines and related deaths can be reduced significantly if improved posture, alignment, sleep quality and fitness were improved. Since twenty five to forty percent of our lives are spent in bed (6-9.6 hours), there is a need for a mattress or Body Support Apparatus that provides softness for desirable comfort while at the same time provides necessary firmness for proper support.
Many types of mattresses, cushions and other therapeutic pads have been developed to treat back pain and poor sleep by attempting to provide both comfort and support for the user and spine with a variety of systems. One such system uses steel springs. A shortfall created by springs is that they create zones of pressure relief with points of peak pressure where the springs meet the user's body. Elaborate attempts to cover up the springs with overlays, padding, ticking, gels, water, foam and multiple layers of additional material have been attempted. However, spring-based mattresses are generally uncomfortable, costly, noisy, heavy or fragile. Another type of mattress is the air mattress. One such embodiment has an air pump necessary to maintain pressure and or to change the firmness of the mattress by adding or removing air. One short fall of such a system is that as pressure is decreased for comfort, support is lost. Alternately, if more support is desired, comfort is lost as the mattress fills with air and becomes harder.
Other mattresses use water, gels, foam or combinations of each in attempt to achieve optimal comfort and support. Foam mattresses include those made from latex (rubber) and polyurethane (petroleum) and viscoelastic (chemically altered polyurethane) being one of the most popular at this time. Viscoelastic mattresses tend to be highly conforming. Viscoelastic foams also retain much body heat, are highly conforming, may have strong off-gassing, fluctuate in resiliency with changes in ambient temperature and are relatively heavy and expensive. Latex mattresses are highly resilient but lack support and are expensive.
Foam is generally available in a range of resiliencies, weights (Density) and Thicknesses (Layer height). The Polyurethane Foam Association's (PFA) Section 4 defines the support characteristics of foam on an Indention Force Deflection (IFD) scale. This scale grades or rates the support characteristics of foam. In particular Section 4.2.2 defines the general standard by which indentation force deflection is measured.